The present invention relates to a method of transferring power to moving electrical loads such as motors or electrical motor components through sliding surfaces of weight-supporting bearings.
The need to transfer electrical power to moving equipment, for example, to an electrical motor that moves with respect to its power source, can occur, for example, in machine tools where the electric motor is mounted on a movable arm or table. A common solution to this problem is the use of flexible cabling communicating between an electric motor and a stationary source of power (for example, a stationary connection to line power). Such cabling can be held, for example, in a flexible cableway to keep it away from engagement with damaging moving surfaces or tangling. Nevertheless, such cable systems can often present an obstruction to the use of the machine and are subject to damage through constant flexure and abrasion.
A similar problem of electrical power transfer can occur in the context of a portion of an electrical motor, for example, a portion that rotates with respect to a stationary power supply. When power must be transferred to a motor rotor, this problem is normally addressed through a system of brushes providing low resistance electrical contact across a sliding surface. Brush systems are highly advanced but are subject to wear and arcing, the latter of which can be a problem in hazardous environments where explosive fumes may accumulate.
U.S. Pat. No. 8,736,137 assigned to the assignee of the present application and hereby incorporated by reference describes a motor (or generator) having air bearings were electrical power is transferred first to the rotor through the air bearings. Such bearings provide an extremely closely fitting shaft and journals having substantial capacitive coupling separated by thin layer of air. High-frequency power is transferred through this capacitive coupling.
Air or other fluid bearings are not practical in a wide variety of bearing applications.